Bicycle chain rings with ramps

ABSTRACT

Disclosed are bicycle chain rings for bicycles having specially shaped ramps with lifting surfaces for improved up-shifting performance. Additional embodiments of the bicycle chain rings of the present invention may be configured with one or more additional features formed within the chain rings including a transition slide, a tapered ramp face, a ramp bridge, a ramp lead, a trailing transition slide and a wear pin.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 13/966,158titled “Bicycle Chain Rings with Ramps” that was filed on Aug. 13, 2013,issued on Sep. 2, 2014 as U.S. Pat. No. 8,821,329 and was a continuationof U.S. patent application Ser. No. 13/338,181, titled, “BICYCLE CHAINRINGS WITH RAMPS”, filed Dec. 27, 2011, and issued Aug. 13, 2013 as U.S.Pat. No. 8,506,436, which in turn is a continuation of U.S. patentapplication Ser. No. 12/284,339, titled, “BICYCLE CHAIN RINGS WITHRAMPS”, filed Sep. 18, 2008, and issued Jan. 10, 2012 as U.S. Pat. No.8,092,329, which in turn is a continuation-in-part (CIP) application ofU.S. patent application Ser. No. 11/397,234, titled “BICYCLE CHAINRINGS,” filed on Apr. 3, 2006, and issued Dec. 31, 2013 as U.S. Pat. No.8,617,015, which in turn claims priority to provisional patentapplication No. 60/721,414, titled “BICYCLE CHAIN RINGS,” filed on Sep.27, 2005. The contents of all of the aforementioned patents and patentapplications are hereby incorporated by reference for all purposes as iffully set forth herein.

This continuation patent application is also related to U.S. designpatent application Ser. No. 29/254,870, titled “BICYCLE CHAIN RINGS,”filed on Mar. 1, 2006, and issued Apr. 17, 2007 as U.S. design Pat. No.D540,718; U.S. design patent application Ser. No. 29/310,958, titled“MEDIUM MOUNTAIN BIKE CHAIN RING”, filed Sep. 18, 2008, and issued Sep.8, 2009 as U.S. design Pat. No. D599,719; U.S. design patent applicationSer. No. 29/310,955, titled “LARGE CYCLOCROSS BIKE CHAIN RING”, filedSep. 18, 2008, and issued Sep. 8, 2009 as U.S. design Pat. No. D599,717;U.S. design patent application Ser. No. 29/310,954, titled “LARGE ROADBIKE CHAIN RING”, filed Sep. 18, 2008, and issued Sep. 8, 2009 as U.S.design Pat. No. D599,716; U.S. design patent application Ser. No.29/310,953, titled “MEDIUM ROAD BIKE CHAIN RING”, filed Sep. 18, 2008,and issued Sep. 1, 2009 as U.S. design Pat. No. D599,255; U.S. designpatent application Ser. No. 29/310,957, titled “LARGE MOUNTAIN BIKECHAIN RING”, filed Sep. 18, 2008, and issued Sep. 8, 2009 as U.S. designPat. No. D599,718. The contents of all of the aforementioned relatedpatents and applications are also incorporated by reference for allpurposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates generally to bicycle chain rings used inbicycle drive trains. More particularly, this invention relates tobicycle chain rings with ramps and other features for improved shiftingperformance.

Description of Related Art

Conventional bicycle gear systems typically include a crankset includingtwo or three chain rings affixed to a crank arm spider and a separatesimple crank arm. The crank arms of a crankset are configured to receivepedals on one end and to be affixed at the other end to a bottom bracketspindle with bearings for rotation. Conventional bicycle gear systemsalso typically include a rear cog set, occasionally referred to as acassette or cluster, having one to ten gears with teeth configured torotate a rear wheel through a hub with bearing mechanism. Conventionalbicycle gear systems further include a bicycle chain that is driven bythe chain rings of the crankset which, in turn, drive the cogs of therear cog set. The gears of the bicycle may be selectively changed usingshifters with control wires attached to front and rear derailleurs thatmove the chain from adjacent chain rings or cogs.

Conventional front derailleurs used with cranksets having two or threechain rings push the chain from one ring to the next using lateralmotion. During an up-shift, for example, the chain guide of a frontderailleur pushes laterally against the side of a chain until the linksof the chain finally catch on a tooth of the larger adjacent chain ringand all subsequent links of the chain follow until the chain is alignedwith the teeth of the larger adjacent chain ring. A down-shift isachieved by pushing laterally against the chain resting on the largerchain ring until the chain can fall down to the smaller chain ring.

This conventional method of pushing laterally against the chain with achain guide provides adequate shifting for most purposes. However, underextreme loading, such as sprinting or out of the saddle climbing, thereis a need for quicker shifting, especially up-shifting. A number ofsolutions have been proposed to improve shifting performance of a frontderailleur.

The inventor of the present application has invented improved frontderailleurs, see e.g., U.S. Pat. Nos. 6,454,671 and 7,025,698, both toWickliffe. These prior patents approach the problem of improved shiftingby changing the way a front derailleur shifts a chain from chain ring tochain ring—by using a chain guide that physically lifts up the bicyclechain during up-shifts, and pulls down the bicycle chain duringdown-shifts. This is in contrast to conventional front derailleurs withtheir predominantly lateral movement of the bicycle chain, during bothup- and down-shifts.

Other approaches to improving front derailleur shifting performance havefocused on redesigning bicycle chains by shaping outer chain links tomore readily grab conventional teeth found on conventional chain rings.By shaping outer chain links of a bicycle chain to bow out laterally orto have chamfered or tapered inner surfaces, such chains may be able tograb chain ring teeth quicker.

Still other approaches to improving front derailleur shiftingperformance have focused on redesigning the chain rings themselves. Forexample, U.S. Pat. No. 5,078,653 to Nagano discloses a larger chain ringwith selected teeth having reduced height relative to adjacent teeth,i.e., the crests of the selected teeth having been uniformly cut off toreduce height. Additionally, a short pin has been inserted into theinside of the larger chain ring just below the trimmed teeth and opposedto the smaller chain ring. The arrangement disclosed in the '653 patent,purports to facilitate quicker down-shifts by allowing the chain todisengage at the trimmed teeth and be lowered onto the teeth of asmaller chain ring via the short pin. However, there is no indicationthat the invention disclosed in the '653 patent improves up-shifting,especially during high loads as mentioned above.

U.S. Pat. No. 6,666,786 to Yahata discloses another improvement todown-shifting performance through the use of chamfered chain ring teeth.However, like the '653 patent, the '786 patent does not address orattempt to solve the problem of achieving improved up-shifting.

U.S. Pat. No. 5,413,534 to Nagano and U.S. Pat. No. 6,572,500 to Tetsukaare directed toward redesigning a conventional chain ring to improveup-shifting. These two patents disclose the use of pins, or a pin incombination with tooth chamfering, to improve up-shifting. However, inboth patents the pin or teeth engage a given chain link at the pointdirectly between chain link rollers. This configuration tends to beproblematic because the load points of a bicycle chain are concentratedat each of the chain link rollers (bushings surrounding pins). Thus, theuse of pins as disclosed in the '534 and '500 patents to Nagano andTetsuka, respectively, may increase stress on the chain especiallyduring high loads and, thus, could lead to increased wear and reducelongevity of the chain.

Similarly, U.S. Pat. No. 5,876,296 to Hsu et al. discloses the use of anaxially oriented recess in combination with a support protrusion to aidin up-shifting. U.S. Pat. No. 5,738,603 to Schmidt et al. discloses achain ring with pins, chamfered teeth and missing teeth to aid inshifting. However, neither of these two patents appears to solve theproblem of the added stress to the chain from the “support protrusion”or the “pins”.

FIG. 30A is a diagram illustrating a conventional chain ring using twopins to aid in shifting a chain during an up-shift. The two pins 1202lift and drop the chain 1210 onto the larger chain ring 1212 during anup-shift. The pins 1202 provide lift in the direction of arrows 1204.The set of two pins 1202 shown in FIG. 30 are generally replicated at alocation 180° opposite on the chain ring 1212. So, in a given rotationof the chain ring 1212, there are only two potential shift points thatcan utilize the pins 1202. Additionally, the load points 1206 aredistributed along the chain pivots 1208. Thus, the lift 1204 provided bypins 1202 do not match the load points 1206 of chain 1210. Whendown-shifting under load with such conventional chain rings, the chain1210 often keeps engaging the teeth 1214 due to tension and the heightof all the teeth 1214 not allowing a front derailleur cage (not shown)to physically move the chain 1210 past the teeth 1214. This results inslower down-shifts, especially under load.

FIG. 30B is a diagram illustrating a “see saw action”, shown at curveddouble headed arrows 1218, that can occur with an unstable lift point1216 of a single pin 1201 of a conventional chain ring (not shown)lifting upon a chain 1210. FIG. 30B also illustrates that a chain 1210is comprised of alternating sets of inner links 1220 and outer links1222. Conventional chain ring pins 1202 can only grab an outer link1222. Pins 1222 ordinarily do not contact an inner link 1220.Consequently, there is approximately a 50% chance the chain 1210 willgrab a pin 1202 and hopefully hold on long enough to engage the teeth1214 (FIG. 30A). As shown in FIG. 30B, conventional chain ring designsput the entire chain load on a small contact area between the pin 1202and an outer link 1222 of the chain 1210. The chain 1210 often slips offthe pin 1202. This problem is most noticeable under load and with wearto the pin 1202.

Accordingly, there still exists a need in the art for a bicycle chainring that achieves improved shifting performance without increasing thestress on the bicycle chain, thereby addressing at least some of theshortcomings of the prior art.

SUMMARY OF THE INVENTION

An embodiment of a bicycle chain ring is disclosed. The chain ring mayinclude ramps disposed about an inner surface of the bicycle chain ringfor engaging one or more outer chain links of a bicycle chain during anup-shift, each ramp configured with a lifting surface and a ramp face,each of the ramps further comprising a transition slide disposed along aleading edge of each ramp, the transition slide forming a bevel taperingthe lifting surface back to a ramp face at an inner periphery of aninner opening of the chain ring.

Another embodiment of a bicycle chain ring is disclosed. The chain ringmay include a ramp formed on an inner surface of the bicycle chain ring,the ramp comprising a raised structure with a lifting surfaceperpendicular to a plane of the inner surface. The chain ring mayfurther include a ramp face adjacent to the lifting surface, the rampface forming a planar surface tapering a thickness of the bicycle chainring in a radial direction. The chain ring may further comprise thelifting surface and ramp face configured for engaging one or more outerchain links of a bicycle chain during an up-shift. The chain ring mayfurther include a wear pin embedded within the raised structure andadjacent the lifting surface for minimizing wear to the lifting surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings illustrate exemplary embodiments for carrying outthe invention. Like reference numerals refer to like parts in differentviews or embodiments of the present invention in the drawings.

FIG. 1 is a plan view of an inner surface of a bicycle chain ringaccording to an embodiment of the present invention.

FIG. 2 is an edge view of a portion of a conventional bicycle chain ringviewed from above the teeth.

FIG. 3 is an edge view of a portion of an embodiment of a bicycle chainring according to the present invention.

FIG. 4 is a plan view of the inside of another embodiment of a bicyclechain ring having 44 teeth configured for a standard 104 mm 4-boltcrankset according to the present invention.

FIG. 5 is a plan view of the outside of the embodiment of the bicyclechain ring shown in FIG. 4.

FIG. 6 is an enlarged perspective view of a portion of the inside of thebicycle chain ring shown in FIG. 4.

FIG. 6a shows the chain ring of FIG. 1 overlaid with a geometric circleand its tangents.

FIG. 7 is a plan view of the inside of yet another embodiment of abicycle chain ring having 32 contoured teeth configured for a standard104 mm 4-bolt crankset according to the present invention.

FIG. 8 is a plan view of the outside of the embodiment of the bicyclechain ring shown in FIG. 7.

FIG. 9 is an enlarged perspective view of a portion of the inside of thebicycle chain ring shown in FIG. 7.

FIG. 10 is a flow chart of an embodiment of a method for up-shifting abicycle chain from a smaller bicycle chain ring to a larger bicyclechain ring.

FIG. 11 is a plan view of the inside of a 32 tooth bicycle chain ring on94 mm mounting bolt centers having five mounting bolt holes according toan embodiment of the present invention.

FIG. 12 is an enlarged perspective view of a portion of the inside ofthe bicycle chain ring shown in FIG. 11.

FIG. 13 is a super-enlarged perspective view of a portion of the insideof the bicycle chain ring shown in FIGS. 11-12.

FIGS. 14-15 are enlarged perspective views of the outside of the bicyclechain ring shown in FIGS. 11-13.

FIG. 16 is a plan view of an embodiment of a 34 tooth bicycle chain ringon 104 mm mounting bolt centers having four mounting holes according toan embodiment of the present invention.

FIG. 17 is a plan view of an embodiment of a 32 tooth bicycle chain ringcompatible with a four mounting hole Shimano™ XTR™ crankset according toan embodiment of the present invention.

FIG. 18 is a plan view of an embodiment of a 34 tooth bicycle chain ringon 94 mm mounting bolt centers having five mounting holes according toan embodiment of the present invention.

FIG. 19 is a plan view of an embodiment of a 34 tooth bicycle chain ringon 104 mm mounting bolt centers having four mounting holes according toan embodiment of the present invention.

FIG. 20 is a plan view of an embodiment of a 34 tooth bicycle chain ringon 110 mm mounting bolt centers having five mounting holes according toan embodiment of the present invention.

FIG. 21 is a plan view of an embodiment of a 34 tooth bicycle chain ringcompatible with a four mounting hole Shimano™ XTR™ crankset according toan embodiment of the present invention.

FIG. 22 is a plan view of an embodiment of a 44 tooth bicycle chain ringon 94 mm mounting bolt centers having five mounting holes according toan embodiment of the present invention.

FIG. 23 is a plan view of an embodiment of a 44 tooth bicycle chain ringon 104 mm mounting bolt centers having four mounting holes according toan embodiment of the present invention.

FIG. 24 is a plan view of an embodiment of a 44 tooth bicycle chain ringon 110 mm mounting bolt centers having five mounting holes according toan embodiment of the present invention.

FIG. 25 is a plan view of an embodiment of a 44 tooth bicycle chain ringcompatible with a four mounting hole Shimano™ XTR™ crankset according toan embodiment of the present invention.

FIG. 26 is a plan view of an embodiment of a 46 tooth bicycle chain ringon 94 mm mounting bolt centers having five mounting holes according toan embodiment of the present invention.

FIG. 27 is a plan view of an embodiment of a 46 tooth bicycle chain ringon 104 mm mounting bolt centers having four mounting holes according toan embodiment of the present invention.

FIG. 28 is a plan view of an embodiment of a 46 tooth bicycle chain ringon 110 mm mounting bolt centers having five mounting holes according toan embodiment of the present invention.

FIG. 29 is a plan view of an embodiment of a 46 tooth bicycle chain ringcompatible with a four mounting hole Shimano™ XTR™ crankset according toan embodiment of the present invention.

FIG. 30A is a diagram illustrating a conventional chain ring using twopins to aid in shifting a chain during an up-shift.

FIG. 30B is a diagram illustrating a problem that can occur with anunstable lift point of a single pin of a conventional chain ring liftingupon a chain.

FIG. 31A is a diagram of an embodiment of a chain ring with rampsaccording to the present invention.

FIG. 31 B is an end-on view of a chain engaging a ramp of a chain ringaccording to an embodiment of the present invention.

FIG. 31C illustrates a few links of a chain with its load points locatedat the chain pivots and corresponding lift points.

FIGS. 32A and 32B are plan views of inner and outer surfaces of apresently preferred embodiment of a 44 tooth bicycle chain ring on 104mm mounting bolt centers (four bolts) according to the presentinvention.

FIGS. 32C and 32D illustrate perspective views of outer and innersurfaces of the chain ring shown in FIGS. 32A and 32B.

FIGS. 33A-33E are outer perspective, inner perspective, outer plan, edgeand inner plan views, respectively, of a presently preferred mediummountain bike chain ring including 32 teeth on 104 mm mounting boltcenters (four bolts).

FIGS. 34A-34E are outer perspective, inner perspective, outer plan, edgeand inner plan views, respectively, of a presently preferred largecyclocross bike chain ring including 44 teeth on 110 mm mounting boltcenters (five bolts).

FIGS. 35A-35E are outer perspective, inner perspective, outer plan, edgeand inner plan views, respectively, of a presently preferred large roadbike chain ring including 53 teeth on 130 mm mounting bolt centers (fivebolts).

FIGS. 36A-36E are outer perspective, inner perspective, outer plan, edgeand inner plan views, respectively, of a presently preferred medium roadbike chain ring including 39 teeth on 130 mm mounting bolt centers (fivebolts).

FIG. 37 is a perspective view of a partial crankset assemblyillustrating assembled embodiments of chain rings according to thepresent invention.

FIG. 38 is an exploded view of the partial crankset assembly of FIG. 37.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention include chain rings for bicycleshaving specially shaped ramps, tapers and profiled teeth for improvedshifting. The embodiments of the chain rings of the present inventionmay be assembled with a crank arm and spider with mounting bolts to forma crankset. The embodiments of the chain rings of the present inventionmay also be retrofitted to existing bicycle cranksets as replacementchain rings and can be configured for any standard bolt on configurationand number of teeth. For example and not by way of limitation, theembodiments of chain rings of the present invention may include middlechain rings in 32 tooth “compact” or 34 tooth “standard” configurationswith either four or five bolt mounting structures. Additionally, theembodiments of chain rings of the present invention may include outer(large or big) chain rings in 44 tooth “compact” or 46 tooth “standard”configurations with either four or five bolt mounting structures. Inroad bike configurations (dual chain ring or “double crankset”), theembodiments of chain rings of the present invention may include outer orlarge chain rings in 53 tooth “standard” configuration or medium chainrings in 39 tooth “standard” configuration, both with five bolt mountingstructures. Of course, any number of teeth or bolt patterns may be usedwith the chain rings of the present invention and all such variationsare considered to be within the scope of the present invention.

FIG. 31A is a partial diagram of an embodiment of a chain ring 1224 withramps according to the present invention. The chain ring 1224 has aplurality of ramps 1226 (three shown in partial view) spread out every3-5 teeth depending on chain ring size and particular location. Thisconfiguration of ramps 1226 spread around the inner surface of the chainring 1224, provides a fast, positive engagement of the chain 1210. Thisfast, positive engagement of the chain 1210 is relatively independent oflocation in the crankset revolution during which a shift of gears isinitiated. FIG. 31A further illustrates that lift points 1204 (solidarrows) on ramp 1226 are equal in number and opposite in direction tothe load points 1206 (solid arrows) from chain 1210. FIG. 31A alsoillustrates a ramp face 1228 and a contoured or low profile tooth 1230above each ramp 1226. The contoured tooth 1230 and ramp face 1228 allowsthe chain 1210 to lean in and mesh smoothly onto the teeth 1214 of chainring 1224. The contoured teeth 1230 of chain ring 1224 allow a frontderailleur cage (not shown) to physically move the chain 1210 past a cutor contoured tooth 1230, thus allowing for faster down-shifts,especially under load.

In FIG. 31A, the flat channel 670 has a minimum width 2012 between thelifting points 1204 and the closest lifting ramp 1226 that is greaterthan the height 2011 of the chain. In FIG. 31A, the maximum channelwidth 2013 between ramps 1226 is shown to be less than about two linkheights 2011.

FIG. 31B is an end-on view of a chain engaging a ramp of a chain ringaccording to an embodiment of the present invention. FIG. 31Cillustrates a few links of a chain 1210 with its load points 1206located at the chain pivots 1208 and corresponding lift points 1204along outer links 1222. The chain has a chain height 2011 ofapproximately twice the distance from a lift point 1204 to the center ofthe closest chain pivot 1208. As can be seen from FIGS. 31B-31C, chainring 1224 lifts the chain 1210 from the bottom corner of the outer links1222 directly below the load points 1206 of the chain 1210. The ramps1226 of chain ring 1224 provide a superior engagement without theslippage of conventional chain ring pins 1202 (FIGS. 30A-30B). The ramps1226 of chain ring 1224 further provide more contact area thanconventional pins 1202 and lift directly below multiple load points 1206of the chain 1210.

An embodiment of a bicycle chain ring is disclosed. The bicycle chainring may include a plurality of ramps disposed about an inner surface ofthe bicycle chain ring, wherein each of the plurality of ramps isconfigured with a lifting surface to engage a plurality of outer chainlinks of a bicycle chain during an up-shift. Lifting surfaces on each ofthe ramps may include linear, bilinear, multilinear, or curved profilesaccording to various embodiments of the bicycle chain ring. The rampsend at a trough or recess between two adjacent teeth according toanother embodiment of the present invention. Furthermore one of the twoadjacent teeth may be partially cutoff, according to yet anotherembodiment of the present invention.

Another embodiment of a bicycle chain ring may include an inside taperin the bicycle chain ring. The inside taper may be located adjacent toeach of the plurality of ramps. The inside taper may provide decreasingbicycle chain ring thickness in a direction opposite normal rotation(forward motion) of the bicycle chain ring during an up-shift. Accordingto another embodiment, the bicycle chain ring may further includepartially cutoff teeth located radially outward from an outer end ofeach of the plurality of ramps. According to another embodiment, thebicycle chain ring may further include a plurality of non-partiallycutoff teeth in between each of the partially cutoff teeth. According toa further embodiment, each non-partially cutoff tooth may have an insidebevel located proximate its tip. According to a still furtherembodiment, the bicycle chain ring may further include outside bevelslocated in tips of all teeth except for the partially cutoff teeth.

Another embodiment of a bicycle chain ring may further include anoutside taper in each tooth immediately adjacent to and in a clockwisedirection from a partially cutoff tooth when viewing an inside surfaceof the bicycle chain ring, see FIGS. 5 and 8 and related discussion,below. Still another embodiment of a bicycle chain ring may furtherinclude angled knife edges in each non-partially cutoff tooth whenviewed from an edge of the bicycle chain ring looking down onto tips ofthe non-partially cutoff teeth, wherein the angled knife edges are notparallel to a plane running through the bicycle chain ring, see FIG. 3and related discussion below. In yet another embodiment of a bicyclechain ring, a channel may be formed in the inside surface of the bicyclechain ring between adjacent ramps.

Embodiments of bicycle chain rings according to the present inventionmay have any suitable number of teeth, but more particularly in therange from 30 to 54 teeth. Embodiments of bicycle chain rings accordingto the present invention may have four or five support structures eachhaving a mounting hole configured for attachment to a crank arm spider.

Embodiments of bicycle chain rings according to the present inventionmay include ramp structural width ranging from about 2 mm to about 30mm. Ramp structural width may be measured in parallel to an insidesurface of the bicycle chain ring and perpendicular to a lifting surfaceof the ramp. Embodiments of bicycle chain rings according to the presentinvention may include ramp structural thickness ranging from about 2 mmto about 5 mm. Ramp structural thickness may be measured perpendicularfrom the inside surface of the bicycle chain ring to the top surface ofa ramp.

FIG. 1 is a plan view of an inner surface of a bicycle chain ring 100according to an embodiment of the present invention. The bicycle chainring 100 may include a circular structural member 102 having a pluralityof contoured teeth 150A-D replicated serially in a clockwise mannerabout a circumference of the circular structural member 102. The bicyclechain ring 100 may further include a plurality of ramps 108 that areraised up from, and regularly disposed about, the inner surface ofcircular structural member 102.

Each of the plurality of ramps 108 may be configured with a liftingsurface 110 to engage a plurality of outer chain links of a bicyclechain (not shown) to aid in lifting the bicycle chain from a smallerchain ring (also not shown) that is concentric but displaced away fromthe inner surface of bicycle chain ring 100. Each lifting surface 110 ofeach ramp 108 may run generally from a periphery 112 of an inner opening120 to an outer end 122 near the base of a partially cutoff tooth 150Das shown in the illustrated embodiment of bicycle chain ring 100.However, lifting surfaces 110 need not extend all the way to theperiphery 112 of inner opening 120, for example, see ramp starts 128.

According to an embodiment of the present invention, lifting surfaces110 may be linear in profile as shown in FIG. 1. Alternatively accordingto another embodiment of bicycle chain ring 400 of the presentinvention, at least one of the lifting surfaces may be multi-linear inprofile (e.g., see 410 in FIG. 4). According to still another embodimentof bicycle chain ring 100 of the present invention, at least one of thelifting surfaces 110 may be arcuate or curved in profile, not shown inFIGS.

According to an embodiment of a bicycle chain ring 100 shown in FIG. 1,each of the plurality of ramps 108 may begin near a support structure104 or at a periphery of an inner opening 112 of the circular structuralmember 102. Each of the plurality of ramps 108 ends at a trough orrecess 114 between teeth 150A and 150D. The thickness and width of thestructure used to form the plurality of ramps 108 may be of any suitabledimension. Furthermore, any suitable material may be used to form thechain rings 100 according to embodiments of the present invention, forexample and not by way of limitation, aluminum, titanium, steel, andcarbon fiber.

According to another embodiment of the present invention, bicycle chainring 100 may further include an inside taper 116 in the circularstructural member 102 located above each of the plurality of ramps 108.The inside taper 116 may be achieved by any suitable means including,but not limited to machining, stamping or investment casting. The insidetaper 116 may be linear in nature and reduce the thickness of thecircular structural member 102 above each ramp 108 in any amount rangingfrom 0 mm to approximately 2 mm. The inside taper 116 may begin, forexample, along the curved lines 117 and extend through teeth 150C and150D to an outer end 122 where the taper is greatest. The inside taper116 provides decreasing circular structural member 102 thickness in adirection opposite normal rotation, R, of the bicycle chain ring 100during an up-shift. See FIG. 3 and related discussion below for furtherillustration of inside taper 116.

According to still another embodiment of the present invention, bicyclechain ring 100 may further include partially cutoff teeth 150D locatedradially above an outer end 122 of each of the plurality of ramps 108.Nonpartially cutoff teeth 150A-C may be found between the partiallycutoff teeth 150D. Generally speaking, all teeth 150A-D shown in FIG. 1are contoured or profiled to improve shifting characteristics asdescribed herein.

FIG. 2 is an edge view of a portion of a conventional bicycle chainring, shown generally at 200, viewed from above the teeth 250. Therelative dimensions of FIG. 2 are not drawn to scale, but areexaggerated for ease of explanation. A conventional bicycle chain ring200 may have an inside surface 240 and an outside surface 242. Aconventional bicycle chain ring 200 may have generally uniform shapedteeth 250 having knife edge points 234 separated by generally uniformlyrounded troughs 236 that support round bushings (not shown) of a bicyclechain (not shown). Conventional bicycle chain rings 200 may also have anouter ridge 238 and/or an inner ridge (not shown) for structuralsupport. FIG. 2 also illustrates a center plane 270 (see dotted line)that is coplanar with knife edge points 234.

In contrast, FIG. 3 is an edge view of a portion of an embodiment of abicycle chain ring 300 according to the present invention (as indicatedon FIG. 1 by bent arrows 3). As with FIG. 2, the relative dimensions ofFIG. 3 are not drawn to scale, but are exaggerated for ease ofexplanation. The view of a portion of bicycle chain ring 300 shown inFIG. 3 illustrates a top view of four adjacent contoured teeth 350A-D.Bicycle chain ring 300 may also have an outer ridge 338, according tothe embodiment shown in FIG. 3. Bicycle chain ring 300 may furtherinclude rounded troughs 336 for supporting cylindrical bushings (notshown) of a bicycle chain (not shown) in between each of the contouredteeth 350A-D. However, the surfaces of rounded troughs 336 are notuniform like the rounded troughs 236 of the conventional bicycle chainring 200 (FIG. 2) because of the additional novel features of thecontoured teeth 350A-D.

The portion of an embodiment of a bicycle chain ring 300 illustrates aramp 308 having a lifting surface 310 for engaging a bicycle chain (notshown) during up-shifts. The ramp 308 with lifting surface 310 is aunique feature that is completely missing from conventional bicyclechain ring 200. While some conventional bicycle chain rings have pins,they still do not have ramps 308 with extended lifting surfaces forengaging multiple links of a bicycle chain. The pins associated withsome conventional bicycle chain rings only engage a single chain ringlink. However, the inside lifting surfaces 110 and 310 of ramps 108 and308 of the embodiments of bicycle chain rings 100 and 300 of the presentinvention are capable of supporting a plurality of bicycle chain links.This feature of embodiments of the present invention provides bettersupport to lift a bicycle chain during up-shifts. This feature isespecially important during hard up-shifts, for example when sprintingor when the rider is out of the saddle during climbing, thereby puttingsubstantial tensile force on the chain.

The lifting surface 310 on ramp 308 is expanded (below the dashed linein FIG. 3) along inside taper 316 (shown generally below bracket in FIG.3). The inside taper 316 is formed in the inside of bicycle chain ring300. The inside taper 316 narrows the overall thickness of the teeth350A-D and troughs (saddles) 336 by a distance, d, defined by a distancemeasured from inside surface 340 (shown in part by dashed line in FIG.3) to the deepest chamfer cut point 352. That inside taper distance, d,may be any amount up to about 2 mm according to various embodiments ofbicycle chain ring 300.

Another feature of bicycle chain ring 300 is the angled knife edges 334of teeth 350A-C. FIG. 3 illustrates a center plane 370 (see dotted line)that clearly shows that the angled knife edges 334 are noncoplanar,i.e., angled knife edges 334 do not fall along the center line 370, butare angled to it. The angling of the knife edges 334 of teeth 350A-Cprovides enhanced bicycle chain meshing during an up-shift because thebicycle chain twists during an up-shift from a smaller to larger chainring. Note that the angling of the knife edges 334 shown in FIG. 3 areexaggerated for ease of explanation and may not actually be angled asgreatly as illustrated. The angling of the knife edges 334 tracks thetwisting of the bicycle chain to more quickly engage the bicycle chainthan without the angled knife edges 334. This feature improvesup-shifting performance (faster) relative to knife edges points 234 (seeFIG. 2) having no angling. This feature may also improve chain meshingwhen the bicycle chain is being driven at an angle relative to rear cogsassociated with a freewheel or cassette mechanism. Poor chain meshing ischaracterized by lack of consistent seating of the bicycle chain introughs 236 and may be caused by the bicycle chain being driven at anangle relative to rear cogs. Poor chain meshing may also becharacterized by increased noise resulting from the lack of consistentseating of the bicycle chain and its cylindrical bushings in troughs236.

Still another feature illustrated in FIG. 3 is outside taper 356 incontoured tooth 350A. Outside taper 356 works in conjunction with a rampto the right of tooth 350A (not shown) to narrow the thickness ofcontoured tooth 350A and thereby making it easier for tooth 350A to grabthe bicycle chain ring 300 during an up-shift. According to anotherembodiment, outside taper 356 may be a short bevel or chamfer along theoutside edge of tooth 350A rather than the taper along the entire widthof tooth 350A shown in FIG. 3. Note that four contoured teeth 350A-D areshown associated with the ramp 308, in FIG. 3. However, any number ofteeth, three to seven may be associated with each ramp according toother embodiments of the present invention. In those other instances,the tooth having an outside taper would be to the left of cutoff tooth350D in the view of FIG. 3. For example, see outside taper 556 in FIG. 5and related discussion below.

Structural thickness, t, of ramps 308 may range from about 2 mm to about5 mm according to embodiments of the present invention. Structuralthickness, t, less than about 2 mm may not provide enough liftingsurface along the ramp 308 for efficient up-shifting. Structuralthickness, t, greater than about 5 mm may cause the bicycle chain tounnecessarily catch when the chain is tracking in smaller chain ringsand angled in toward the larger chain ring because of rear cogalignment.

Referring to FIGS. 1 and 3, partially cutoff teeth 150D and 350D do nothave a knife edge 334 because the upper portion of teeth 150D and 350Dhave been removed. The purpose for reducing the profile of teeth 150Dand 350D by partially cutting off the upper portion of teeth 150D and350D is to provide a point of lateral entry of the bicycle chain overthe bicycle chain ring 100 and 300 during an up-shift. Thus, thepartially cutoff teeth 150D and 350D encourage lateral movement of thebicycle chain from a small bicycle chain ring onto bicycle chain rings100 and 300. This encouraging of lateral movement improves shiftingperformance over conventional bicycle chain rings such as the oneillustrated in FIG. 2, where all of the teeth 250 are of identicalheight profile. Incidentally, the partially cutoff teeth 150D and 350Dalso improve down-shifting for essentially the same reason: encouraginglateral movement of the bicycle chain. However, during a down-shift, thebicycle chain is urged off of bicycle chain ring 300.

Embodiments of bicycle chain rings 100 and 300 illustrated in FIGS. 1and 3 may have three contoured teeth 150B-D and 350B-D or four contouredteeth 150A-D and 350A-D associated with each ramp 108 and 308. However,other combinations and numbers of contoured teeth 150A-D and 350A-D maybe associated with ramps 108 and 308 consistent with the presentinvention. Such other combinations and numbers of contoured teeth areconsidered to be within the spirit and scope of the present invention.

FIG. 4 is a plan view of the inside of another embodiment of a bicyclechain ring 400 having 44 contoured teeth 450A-D configured for astandard 104 mm 4-bolt crankset according to the present invention.Bicycle chain ring 400 may be used as a large chain ring on a mountainbike crankset. It will be readily apparent to one of ordinary skill inthe art that the invention is not limited to any particular mountingbolt pattern, mounting bolt number, number of teeth or bolt patternradius.

Contoured teeth 450A-D may include inside bevels 460 along the tips toachieve the angled knife edges (334 in FIG. 3) as a feature of thepresent invention. Inside bevels 460 form portions of the angled knifeedges (334 in FIG. 3) that improve bicycle chain meshing as describedherein. Inside bevels 460 may be of any shape that improves bicyclechain meshing and therefore reduces noise and improves shiftingperformance relative to bicycle chain rings without such features.

According to the embodiment of bicycle chain ring 400, ramps 408 may belinear profile ramps 408A or bilinear profile ramps 408B. The bilinearprofile ramps 408B may be partially formed on support structures 104,thus allowing for longer ramps and bilinear configurations. Ramps 408A-Bmay include gaps (not shown) according to other embodiments of bicyclechain ring 400, but each ramp 408A-B always supports more than a singlelink as distinguished from pins used in prior art chain rings. FIG. 4also illustrates structural members 104 (four shown) and theirassociated mounting holes 106.

FIG. 4 also illustrates the regions of inside taper 416 adjacent thelifting surface 410 of each ramp 408A-B. Inside taper 416 may take anyform or shape that narrows the thickness of the bicycle chain ring 400above the ramps 408A-B according to various embodiments of the presentinvention. See also FIG. 6 and related discussion below for an enlargedview of inside taper 416. The structural width, w, of any given ramp408A-B may be of any suitable dimension that provides consistent supportof a bicycle chain. Any structural width, w, less than about 2 mm, maylack suitable wear characteristics for use on bicycles over extendedperiods of time. Structural width, w, may vary from among the ramps 408located on a single bicycle chain ring 400 according to otherembodiments of the present invention, e.g., see FIGS. 7 and 9, below.Structural width, w, may fall within the range from about 2 mm to about30 mm according to various embodiments of the present invention.

FIG. 5 is a plan view of the outside of the embodiment of the bicyclechain ring 400 shown in FIG. 4. In the view of FIG. 5, outer ridge 538appears as a circle underneath contoured teeth 450A-D. FIG. 5 alsoillustrates structural members 104 (four shown) and their associatedmounting holes 106. FIG. 5 further illustrates the outside bevel 554 ofcontoured teeth 450, particularly contoured teeth 450A-C and notincluding partially cutoff teeth 450D (i.e., all teeth other than cutoffteeth 450D). Outside bevel 554 provides enhanced bicycle chain meshingas described above. Another feature of bicycle chain ring 400illustrated in FIG. 5 is outside taper 556. Outside taper 556 isassociated with contoured teeth 450A or 450B, depending on the number ofcontoured teeth (three or four) associated with a given ramp 408.Outside taper 556 narrows contoured teeth 450A or 450B at a positionadjacent to cutoff teeth 450D. The outside taper 556 is configured tograb the inside of a bicycle chain link between cylindrical bushings.Thus, outside taper 556 can more quickly grab the bicycle chain (notshown) during an up-shift because the profile of contoured teeth 450A or450B is narrower. Outside taper 556 may also improve chain meshing asdescribed above. Embodiments of outside taper 556 may encompass most ofthe body of contoured teeth 450A or 450B as shown in bicycle chain ring400 of FIG. 5. Alternatively, outside taper 556 may be a smallerchamfer, bevel or notch (not shown in FIG. 5, but see FIG. 8 and outsidenotch 856) on the body of contoured teeth 450A or 450B nearest contouredteeth 450D according to other embodiments of the present invention.

FIG. 6 is a perspective view of a portion of the inside of the bicyclechain ring 400 shown in FIG. 4, enlarged to show detail. The portion ofthe bicycle chain ring 400 shown in FIG. 6 includes two ramps 408, morespecifically a linear profile ramp 408A and a bilinear profiled ramp408B. FIG. 6 also illustrates a support structure 104, a mounting hole106, a lifting surface 410 on each ramp 408A-B, contoured teeth 450A-D,inside bevels 460 associated with contoured teeth 450A-C and insidetaper 416 adjacent ramps 408A-B. FIG. 6 further illustrates a channel670 on the ramp face (1310, see FIG. 32A) that is formed betweenadjacent ramps 408A-B on the inside surface of bicycle chain ring 400according to the present invention. Channel 670 provides a space for thebicycle chain during up-shifts. The ramp face includes a first planarportion 2015 connecting to a second planar portion 2016 at a transition2017. The height 2018 of the ramp 410 adjacent to the second planarportion 2016 is greater than the height 2018 of the ramp 410 adjacent tothe first planar portion 2015. The channel 670 is bounded by the ramp408A, the periphery 112, and the side 2014 of a closest element (ramp408A in the illustrated example) extending from the first planar portion2015. The side 2014 and the ramp 408A extend outwardly from the firstplanar portion 2015 in generally the same direction away from the centerplane of the chain ring. The first planar portion 2015 and the channel670 both have a width 2012 between the ramp 408B and the side 2014 oframp 408A. FIG. 6a shows the chain ring of FIG. 1 overlaid with ageometric circle 3000 having a center 3001 located at the axis ofrotation of the chain ring and a plurality of geometric tangents 3002.As shown in FIG. 6a , each of the lifting surface 110 of the chain ringis aligned with one of the tangents 3002 of the geometric circle 3000.

FIG. 7 is a plan view of the inside of yet another embodiment of abicycle chain ring 700 having 32 contoured teeth 750A-D configured for astandard 104 mm 4-bolt crankset according to the present invention.Bicycle chain ring 700 may be configured as a middle chain ring on amountain bike crankset Bicycle chain rings 400 and 700 together may forma compact set of chain rings for a mountain bike crankset Bicycle chainring 700 may include a circular structural member 702, a plurality ofsupport structures 704 (four shown), each with mounting holes 106 (fourshown). Bicycle chain ring 700 may further include ramps 708A-B (eighttotal: four ramps 708A and four ramps 708B) of various widths, w,depending on the location of the ramp 708A-B. For example and not by wayof limitation, ramp 708A may include relatively narrow width, w₁.Whereas ramp 708B may have a relatively wide width, w₂, that encompassesmounting hole 106, as shown in FIG. 7. As noted above, ramp structuralwidth, w, w₁ or w₂, may be anywhere in the range from about 2 mm toabout 30 mm. Structural thickness (not shown in FIG. 7) of ramps 708A-Bmay be as described above for the embodiment of bicycle chain ring 300in FIG. 3.

Referring again to FIG. 7, each ramp 708A-B is configured with a liftingsurface 710. Each ramp 708A-B may be associated with three or fivecontoured teeth 750A-E depending on the size and location of theassociated ramp 708A-B. Partially cutoff teeth 750E are separated bynonpartially cutoff, contoured teeth 750A-D. Of course, contoured teeth750A-E shown in the embodiment of FIG. 7, may have similar features andcharacteristics to contoured teeth 150A-D, 350A-D and 450A-D, as otherembodiments described above. Bicycle chain ring 700 may further haveinside tapers 716 adjacent the lifting surfaces 710 of each ramp 708A-B.Inside tapers 716 may have similar features and characteristics toinside tapers 116 (FIG. 1) and 316 (FIG. 3) described above. FIG. 7 alsoillustrates support structures 704 and associated mounting holes 106.

FIG. 8 is a plan view of the outside of the embodiment of the bicyclechain ring 700 shown in FIG. 7. In the view of FIG. 8, outer ridge 838appears as a circle underneath contoured teeth 750A-E. FIG. 8 alsoillustrates the outside bevel 854 of contoured teeth 750, particularlycontoured teeth 750A-D and not including partially cutoff teeth 750E(i.e., all teeth other than cutoff teeth 750E). Outside bevel 854provides enhanced bicycle chain meshing as described above. FIG. 8 alsoillustrates outside notch 856. Outside notch 856 is associated withcontoured teeth 750A or 750C depending on the number of contoured teeth(three or five) associated with a given ramp 708 (not shown in FIG. 8).Outside notch 856 narrows contoured teeth 750A or 750C at a positionadjacent to cutoff teeth 750E. The outside notch 856 is configured tograb the inside of a bicycle chain link between cylindrical bushings(not shown) in the chain (also not shown). Thus, outside notch 856 canmore quickly engage the bicycle chain (not shown) during an up-shift,because the profile of contoured teeth 750A or 750C is narrower. Outsidenotch 856 may also improve chain meshing as described above. Otherembodiments of outside notch 856 may encompass most of the body ofcontoured teeth 750A or 750C as shown in outside taper 556 of bicyclechain ring 400 of FIG. 5. FIG. 8 also illustrates support structures 704and associated mounting holes 106.

Referring now to FIG. 9, a perspective view of a portion of the insideof the bicycle chain ring 700 of FIG. 7 is enlarged to show detail. Theportion of the bicycle chain ring 700 shown in FIG. 9 includes twolinear ramps 708A-B, more specifically a narrow width (w₁) linearprofile ramp 708A and a wide width (w₂) linear profiled ramp 708B (seealso FIG. 7). FIG. 9 also illustrates a support structure 704, amounting hole 106, a lifting surface 710 on each ramp 708A-B, contouredteeth 750A-E and inside taper 716 adjacent ramps 708A-B. FIG. 9 furtherillustrates a channel 970 that is formed between adjacent ramps 708A-Bon the inside surface of bicycle chain ring 700 according to the presentinvention. Channel 970 provides a space for the bicycle chain duringup-shifts.

Referring generally to FIGS. 1 and 3-7, embodiments of bicycle chainrings, 100, 300, 400 and 700 include between two and five nonpartiallycutoff, contoured teeth 150A-C, 350A-C, 450A-C and 750A-D (see FIG. 11below for an example of five nonpartially cutoff teeth) separating anytwo nearest cutoff teeth 150D, 350D, 450D and 750E. The centers ofmounting holes 106 may be on the circumference of a circle 104 mm indiameter according to a particular embodiment of the bicycle chain ringsof the present invention. According to alternative embodiments, centersof mounting holes 106 may be on the circumference of a circle 94 mm or110 mm in diameter. The bicycle chain rings 100, 300, 400 and 700disclosed herein may be configured for compatibility with anycommercially available crankset, for example and not by way oflimitation, cranksets manufactured by Shimano™, Campagnolo™, Race Face™,Truvative™, Richey™, Nashbar™, FSA™, and any other manufacturer or modelof crankset.

Yet another feature of the partially cutoff teeth 150D, 350D, 450D and750E disclosed herein is the angle, 0, at which such teeth are cutoff.Referring specifically to FIG. 7, note that angle, 0, is shown asmeasured from tangential line, l₁, to angled line, l₂, traced throughthe top of partially cutoff teeth 750E. By partially cutting off teeth750E at angle, 0, the bicycle chain is given the clearance it needsduring a down-shift to be able to move laterally past the partiallycutoff tooth 750E and drop off chain ring 700 to engage the next smallerchain ring (not shown). During a down-shift, the partially cutoff tooth750E allows an entire chain link to move laterally towards the inside ofbicycle chain ring 700 and past the partially cutoff tooth 750E withoutmaking contact with tooth 750E. This feature promotes fasterdown-shifts. The angled (θ) cutoff teeth 750E are preferred overtangentially cutoff teeth of the prior art (see e.g., U.S. Pat. No.5,078,653 to Nagano as discussed above in the background) because thebicycle chain comes off of chain ring 700 at an angle approximated byangle, 0, not tangentially, during a down-shift.

FIG. 10 is a flow chart of an embodiment of a method 1000 forup-shifting a bicycle chain from a smaller bicycle chain ring to alarger bicycle chain ring. Method 1000 may include providing 1002 alarger bicycle chain ring as described herein. Method 1000 may furtherinclude rotating 1004 a crankset including the smaller and largerbicycle chain rings in a forward motion direction. Method 1000 mayfurther include urging 1006 the bicycle chain toward the inner surfaceof the larger bicycle chain ring. This urging 1006 may be achieved byactivating a front derailleur having a chain guide that pushes laterallyagainst the sides of a bicycle chain. Alternatively, urging 1006 may beachieved by activating a front derailleur such as those described inU.S. Pat. No. 6,454,671 and U.S. Published Patent Application No.US20020177498, both to the present inventor, Christopher A. Wickliffe,thereby lifting a lower outside corner of a bicycle chain toward thelarger bicycle chain ring. Method 1000 may further include multipleouter chain links of the bicycle chain engaging 1008 a lifting surfaceon a ramp and lifting 1010 the bicycle chain off of the smaller bicyclechain ring and onto the larger bicycle chain ring.

Additional embodiments of bicycle chain rings according to the presentinvention are shown in FIGS. 11-29. FIG. 11 is a plan view of the insideof a 32 tooth bicycle chain ring 1100 on 94 mm mounting bolt centershaving five mounting bolt holes according to an embodiment of thepresent invention. FIG. 12 is an enlarged perspective view of a portionof the inside of the bicycle chain ring 1100 shown in FIG. 11. FIG. 12provides an enlarged illustration of mounting hole 106, ramps 1108A and1108B, and inside taper 1116 associated with this embodiment of abicycle chain ring 1100. FIG. 13 is a super-enlarged perspective view ofa portion of the inside of the bicycle chain ring 1100 shown in FIGS.11-12. FIG. 13 illustrates inside taper 1116, mounting hole 106 and ramp1108A. FIGS. 14-15 are enlarged perspective views of the outside of thebicycle chain ring 1100 shown in FIGS. 11-13. FIGS. 14-15 show anenlarged perspective view of outer ridge 1138, outside bevels 1154 andoutside notch 1156. FIG. 15 also shows mounting hole 106 and anobstructed view of inside taper 1116.

It is important to note that the ramps 108, 308, 408A-B, 708A-B and1108A-B, on the inside surface of the bicycle chain rings 100, 300, 400,700 and 1100 disclosed herein, contact and lift the bicycle chaindirectly underneath the load points, i.e., chain link rollers (bushingsand pins), of multiple chain links during an up-shift. Each ramp engagesthe bicycle chain directly below the chain link rollers and lifts atmultiple load points (below each chain link roller). This is in distinctcontrast to conventional bicycle chain rings with pins that attempt toaccomplish the same task. Such conventional pin lifting is necessarilyat a single load point (between two chain link rollers) to accomplishthe bicycle chain lifting. Thus, the ramps 108, 308, 408A-B, 708A-B and1108A-B, of the present invention spread the load over multiple loadpoints.

FIG. 16 is a plan view of an embodiment of a 34 tooth bicycle chain ringon 104 mm mounting bolt centers having four mounting holes according toan embodiment of the present invention. FIG. 17 is a plan view of anembodiment of a 32 tooth bicycle chain ring compatible with a fourmounting hole Shimano™ XTR™ crankset according to an embodiment of thepresent invention. FIG. 18 is a plan view of an embodiment of a 34 toothbicycle chain ring on 94 mm mounting bolt centers having five mountingholes according to an embodiment of the present invention. FIG. 19 is aplan view of an embodiment of a 34 tooth bicycle chain ring on 104 mmmounting bolt centers having four mounting holes according to anembodiment of the present invention. FIG. 20 is a plan view of anembodiment of a 34 tooth bicycle chain ring on 110 mm mounting boltcenters having five mounting holes according to an embodiment of thepresent invention. FIG. 21 is a plan view of an embodiment of a 34 toothbicycle chain ring compatible with a four mounting hole Shimano™ XTR™crankset according to an embodiment of the present invention. FIG. 22 isa plan view of an embodiment of a 44 tooth bicycle chain ring on 94 mmmounting bolt centers having five mounting holes according to anembodiment of the present invention. FIG. 23 is a plan view of anembodiment of a 44 tooth bicycle chain ring on 104 mm mounting boltcenters having four mounting holes according to an embodiment of thepresent invention. FIG. 24 is a plan view of an embodiment of a 44 toothbicycle chain ring on 110 mm mounting bolt centers having five mountingholes according to an embodiment of the present invention. FIG. 25 is aplan view of an embodiment of a 44 tooth bicycle chain ring compatiblewith a four mounting hole Shimano™ XTR™ crankset according to anembodiment of the present invention. FIG. 26 is a plan view of anembodiment of a 46 tooth bicycle chain ring on 94 mm mounting boltcenters having five mounting holes according to an embodiment of thepresent invention. FIG. 27 is a plan view of an embodiment of a 46 toothbicycle chain ring on 104 mm mounting bolt centers having four mountingholes according to an embodiment of the present invention. FIG. 28 is aplan view of an embodiment of a 46 tooth bicycle chain ring on 110 mmmounting bolt centers having five mounting holes according to anembodiment of the present invention. FIG. 29 is a plan view of anembodiment of a 46 tooth bicycle chain ring compatible with a fourmounting hole Shimano™ XTR™ crankset according to an embodiment of thepresent invention.

Referring now to FIGS. 32A-32B, plan views of inner and outer surfaces,respectively, of a presently preferred embodiment of a 44 tooth bicyclechain ring 1300 on 104 mm mounting bolt centers (four bolts) are shownaccording to the present invention. FIGS. 32C and 32D illustrateperspective views of outer and inner surfaces of chain ring 1300. FIGS.32A-32D illustrate some previously discussed three-dimensional surfacefeatures of the present invention including ramps 1304, inner opening1308, periphery 1306 of inner opening 1308, ramp faces 1310, contouredteeth 1314 and mounting holes 1326. FIGS. 32A and 32B also illustratecatch pin 1328 which is a feature common to most large chain rings toprevent a chain from getting caught between the chain ring and crank armspider on an overshoot during an up-shift that can occur with animproperly adjusted front derailleur. Highlighted in FIG. 32D is adivided ramp 2000 having a first ramp portion 2001 and a second rampportion 2002 separated by a gap 2003. The lifting surfaces of the firstramp portion 2001 and the second ramp portion 2002 are radiallyextending and generally coplanar. In FIG. 32D, the gap 2003 in thedivided ramp 2000 is substantially defined by a hole 2020 or lighteningelement extending through a support structure with a mounting hole 106.In the illustrated example, the chain channel 2023 adjacent to the ramphas a leading edge 2021 of a flat guide surface that is substantiallyparallel to the trailing edge 2022 of the flat guide surface of thechain channel 2023. The leading edge inwardly slants from the chainchannel 2023 towards the center plane 270, 370 (see FIGS. 2 and 3) whilethe trailing edge 2022 extends outward from the chain channel 2023 awayfrom the center plane. The trailing edge being substantially defined bythe first ramp portion 2001 and the second ramp portion 2002.

FIG. 32A also illustrates a number of additional novel features of chainring 1300. These additional novel features of chain ring 1300 will becompared or contrasted with respect to the embodiment of a chain ring400 shown in FIG. 4 (discussed above) which does not include theseadditional novel features.

One such novel feature is referred to as a “transition slide” 1302 whichreduces chain snag during shifting. Each transition slide 1302 is abevel located at a leading edge of ramp 1304 adjacent to the periphery1306 of the inner opening 1308 in the chain ring 1300. The transitionslide 1302 tapers the thickness of the leading edge of ramp 1304 fromits full thickness to the surface of ramp face 1310. Transition slide1302 smoothes or removes a sharp corner located on the leading edge ofthe embodiments of ramps 408A and 408B, FIG. 4. By incorporatingtransition slides 1302 at the leading edge of a ramp 1304, there is lessopportunity for a chain (not shown in FIGS. 32A-32B) to becomeunintentionally snagged or dragged by the sharp corner of ramps, e.g.,408A and 408B, FIG. 4.

Another feature of chain ring 1300 is referred to herein as a “rampbridge” 1312 which helps prevent a problem known in the bicycle industryas “chain suck”, which can occur near the completion of a shift. Theconcept of chain suck may be explained by viewing the bicycle from theleft side (from the rider's perspective), where the front derailleur isat the 1 o'clock position, to begin an up-shift during forward rotationof the crankset. As the chain climbs up the ramp and engages thecontoured teeth of the larger chain ring, the chain remains on the rampand partially still on the smaller chain ring as the crankset rotatescounterclockwise. At the end of the shifting rotation, i.e., at the 6o'clock position, of chain ring 400, the chain that is trying to falloff of the smaller chain ring, while simultaneously being pulled by theramp 408A or 408B, will sometimes catch on the back end 425 (FIG. 4) oframp 408A or 408B and be pulled up to the 4 o'clock or 3 o'clockposition, instead of dropping off and traveling back to the rearderailleur.

Each ramp bridge 1312 forms a smoothed raised portion of the chain ring1300 located below its associated ramp 1304, and between the ramp 1304and an adjacent ramp lead 1318 (discussed in further detail below). Theramp bridge 1312, like transition slide 1302, helps prevent chain snagsand particularly chain suck as described above during forward pedaling.Each ramp bridge 1312 also includes a trailing transition slide 1316,which, like the transition slide 1302, is a bevel or taper that smoothesthe ramp bridge 1312 down to the ramp face 1310. The trailing transitionslide 1316 prevents the chain from catching when backpedaling,especially cross chaining.

Still another three-dimensional feature is the ramp lead 1318 which hasthe appearance of a “Nike Swoosh” logo as viewed in FIG. 32A. The ramplead 1318 is a recessed transition from the tapered trailing edge 1320of ramp 1304 (left of “Swoosh”), to the ramp bridge 1312 (bent portionof “Swoosh”) along a region roughly parallel to the next ramp 1304. Theramp lead 1318 is tapered from a flat plane region 1322 (inside of“Swoosh”) to a radially tapered outside surface which forms the rampface 1310. The tapering of the ramp lead 1318 from the flat plane region1322 to the ramp face 1310 reduces chain drag and allows the chain (notshown) to fall along the ramp face 1310 and rest upon the ramp 1304without snagging. The ramp leads 1318 illustrated in FIG. 32A alsoprovide a weight savings by reducing the material on the chain ring 1300above and below adjacent ramps 1304. It will be understood that variousother embodiments of gradually smoothed structures may replace the ramplead 1318 and flat plane region 1322 to form a smooth transition for thechain dropping onto the ramp 1304, consistent with the principles of thepresent invention. The perspective view of FIG. 33D illustrates liftingsurfaces 1336 of ramps 1304 at approximately 11 o'clock and 12 o'clock.

Still another novel feature of chain ring 1300 is the optionalincorporation of wear pins 1324 (FIGS. 32A and 32B) formed into each ofthe ramp 1304 structures. The wear pins 1324 may be formed of any hardmaterial such as stainless steel or titanium. The purpose for the wearpins 1324 is to minimize wearing of the softer aluminum material fromwhich the chain ring 1300 may be formed. Wear pins 1324 may beunnecessary for embodiments of chain rings 1300 formed of otherinherently hard materials, such as titanium, stainless steel, ceramics,or carbon fiber.

FIG. 32B further illustrates cut-away regions 1334, that provide weightsavings and also decorative aesthetics to the outer surface of chainring 1300. Referring again to FIG. 32A, a plurality of “lighteningpockets” 1330 or circular drill-outs (that do not pass completelythrough chain ring 1300) and fluting 1332 are included in regions aroundthe mounting holes 1326. Lightening pockets 1330 and fluting 1332 do notimprove shifting performance, but do reduce overall weight of chain ring1300. The shape and configurations of all such weight-saving features1330, 1332 and 1334 may take many forms consistent with the presentinvention. It will be understood that the configurations ofweight-saving features 1330, 1332 and 1334 shown in FIGS. 32A and 32Bare merely exemplary and not intending to be limiting of the scope ofthe present invention.

While the novel features discussed above have been shown with respect toa 44 tooth bicycle chain ring 1300 on 104 mm mounting bolt centers (fourbolts), it will be readily apparent to one of ordinary skill in the artthat such novel features may be applied to other sizes and applicationsof bicycle chain rings. FIGS. 33A-36E illustrate exemplary embodimentsof such other sizes and applications for the novel features of thebicycle chain rings with ramps of the present invention.

FIGS. 33A-33E are outer perspective, inner perspective, outer plan, edgeand inner plan views, respectively, of a presently preferred mediummountain bike chain ring 1500 including 32 teeth on 104 mm mounting boltcenters (four bolts). In particular, FIGS. 33A and 33B, illustratevarious features of chain ring 1500 including: contoured teeth 1314,lifting surface 1336 on ramp 1304, mounting holes 1330, flat planeregion 1322, ramp lead 1318, ramp face 1310, ramp bridge 1312 andtrailing transition slide 1316. The edge view of FIG. 33D clearly showsthe three-dimensional aspect of the various surface features on bothsides of chain ring 1500.

FIGS. 34A-34E are outer perspective, inner perspective, outer plan, edgeand inner plan views, respectively, of a presently preferred largecyclocross bike chain ring 1600 including 44 teeth on 110 mm mountingbolt centers (five bolts). FIGS. 34A and 34B, illustrate variousfeatures of chain ring 1600 including: contoured teeth 1314, liftingsurface 1336 on ramp 1304, mounting holes 1330, flat plane region 1322,ramp lead 1318 and ramp face 1310. The edge view of FIG. 34D clearlyshows the three-dimensional aspect of the various surface features onboth sides of chain ring 1600.

FIGS. 35A-35E are outer perspective, inner perspective, outer plan, edgeand inner plan views, respectively, of a presently preferred large roadbike chain ring 1700 including 53 teeth on 130 mm mounting bolt centers(five bolts). FIGS. 35A and 35B, illustrate various features of chainring 1700 including: contoured teeth 1314, lifting surface 1336 on ramp1304, transition slide 1302, mounting holes 1330, flat plane region1322, ramp lead 1318, ramp face 1310, ramp bridge 1312 and trailingtransition slide 1316. FIGS. 35B and 35E further illustrate linearfluting 1702 for weight reduction. The edge view of FIG. 35D clearlyshows the three-dimensional aspect of the various surface features onboth sides of chain ring 1700.

FIGS. 36A-36E are outer perspective, inner perspective, outer plan, edgeand inner plan views, respectively, of a presently preferred medium roadbike chain ring 1800 including 39 teeth on 130 mm mounting bolt centers(five bolts). FIGS. 36A and 36B, illustrate various features of chainring 1800 including: contoured teeth 1314, lifting surface 1336 on ramp1304, transition slide 1302, mounting holes 1330, flat plane region1322, ramp lead 1318, ramp face 1310 and ramp bridge 1312. The edge viewof FIG. 36D clearly shows the three-dimensional aspect of the varioussurface features on both sides of chain ring 1800.

FIG. 37 is a perspective view of a partial crankset assembly 1400illustrating assembled embodiments of chain rings according to thepresent invention. The partial crankset assembly 1400 includes a crankarm spider 1402, a bottom bracket spindle 1404, a large mountain bikechain ring 1300, a medium mountain bike chain ring 1500 and a smallmountain bike chain ring 1406. A complete mountain bike crankset (notshown) would include another crank arm (not shown to simplify FIG. 37)that would be configured to attach to the bottom bracket spindle 1404.Such crank arms are well known to those of ordinary skill in the art.

FIG. 38 is an exploded view of the partial crankset assembly 1400 ofFIG. 37. FIG. 38 illustrates a crank arm spider 1402, a bottom bracketspindle 1404, a large mountain bike chain ring 1300, a medium mountainbike chain ring 1500, a small mountain bike chain ring 1406 andfasteners 1408, 1410 and 1412. Fasteners 1408, 1410 and 1412 may be nutsand bolts of any suitable kind known to those of ordinary skill in theart.

While the foregoing advantages of the present invention are manifestedin the illustrated embodiments of the invention, a variety of changescan be made to the configuration, design and construction of theinvention to achieve those advantages. Hence, reference herein tospecific details of the structure and function of the present inventionis by way of example only and not by way of limitation.

We claim:
 1. A bicycle chain ring for engaging a chain link of a bicyclechain, the bicycle chain ring comprising: a plurality of ramps disposedabout an inner surface of the bicycle chain ring, wherein at least oneof the plurality of ramps is configured with a linear lifting surfacethat extends perpendicularly from the inner surface and is configured toconcurrently engage the chain link at two or more distinct pivot pointsalong the length of the chain link, and wherein the at least one ramp ispositioned generally from an inner periphery of the chain ring toward anouter periphery, the at least one ramp ending before reaching the bottomof a trough positioned between chain ring teeth along the outerperiphery.
 2. The bicycle chain ring according to claim 1, wherein atleast one of the lifting surfaces is multi-linear in profile when viewedalong an axis of rotation.
 3. The bicycle chain ring according to claim1, wherein at least one of the ramps has a structural width ranging from2 mm to 30 mm, the structural width being measured in parallel to aninside surface of the bicycle chain ring and perpendicular to thelifting surface of the ramp.
 4. The bicycle chain ring according toclaim 1, wherein at least one of the ramps has a structural thicknessranging from 2 mm to 5 mm, the structural thickness being measuredperpendicularly from an inside surface of the bicycle chain ring to atop surface of the ramp.
 5. The bicycle chain ring according to claim 1,wherein at least one of the plurality of ramps begins at a first radiusmeasured from an axis of rotation and ends at a second radius measuredfrom the axis of rotation, the first radius being less than the secondradius.
 6. The bicycle chain ring according to claim 1, wherein thelifting surface is configured to initiate a stable lift of the bicyclechain without assistance from chain ring teeth or shift pins during anup-shift.
 7. The bicycle chain ring according to claim 6, wherein thelifting surface is configured to concurrently engage two or more loadpoints of the bicycle chain below bicycle chain link pins.
 8. Thebicycle chain ring according to claim 7, wherein the two or moredistinctive points along the length of the chain link correspond to thetwo or more load points of the bicycle chain below the bicycle chainlink pins.
 9. A bicycle chain ring, comprising: a plurality of liftingsurfaces perpendicularly disposed about an inner surface of the bicyclechain ring, at least one of the lifting surfaces being configured toconcurrently engage two or more load points of a bicycle chain belowbicycle chain link pins, thereby initiating stable lift to the bicyclechain without assistance from chain ring teeth or shift pins during anup-shift; and wherein at least one of the plurality of lifting surfacesis linearly positioned generally from an inner periphery toward an outerperiphery, the at least one lifting surface ending before reaching thebottom of a trough positioned between chain ring teeth along the outerperiphery.
 10. The bicycle chain ring according to claim 9, wherein atleast one of the plurality of lifting surfaces begins at a first radiusmeasured from the axis of rotation and ends at a second radius measuredfrom the axis of rotation, the first radius being less than the secondradius.
 11. The bicycle chain ring according to claim 10, wherein thefirst radius is greater than a smaller adjacent chain ring radius. 12.The bicycle chain ring according to claim 9, wherein at least one of thelifting surfaces is multi-linear in profile when viewed along the axisof rotation.
 13. The bicycle chain ring according to claim 9, wherein atleast one of the plurality of lifting surfaces is formed from a ramphaving a structural width as measured in parallel to an inside surfaceof the bicycle chain ring and perpendicular to the lifting surface thatranges from 2 mm to 30 mm.
 14. A bicycle chain ring, comprising aplurality of ramps disposed about an inner surface of the bicycle chainring and positioned generally from an inner periphery of the chain ringtoward an outer periphery, wherein at least one of the plurality oframps is configured with a lifting surface that protrudes from the innersurface and is linearly angled to engage and lift a bicycle chain duringan up-shift, the lifting surface being configured to concurrently engagethe chain at two or more load points along a length of the chain duringthe up-shift, the load points being located directly under chain pivotpoints that are proximate to bicycle chain link pins; and wherein the atleast one ramp ends before reaching the bottom of a trough positionedbetween chain ring teeth along the outer periphery.
 15. The bicyclechain ring according to claim 14, wherein the lifting surface begins ata first radius as measured from an axis of rotation and extends outwardto a second radius, the second radius being greater than the firstradius.
 16. The bicycle chain ring according to claim 15, wherein thefirst radius is greater than a smaller adjacent chain ring radius. 17.The bicycle chain ring according to claim 14, wherein the liftingsurface is configured to initiate a stable lift of the bicycle chainwithout assistance from chain ring teeth or shift pins during theup-shift.
 18. The bicycle chain ring according to claim 14, wherein thelifting surface perpendicularly protrudes from the inner surface. 19.The bicycle chain ring according to claim 14, wherein at least one ofthe ramps has a structural width ranging from 2 mm to 30 mm, thestructural width being measured in parallel to an inside surface of thebicycle chain ring and perpendicular to the lifting surface of the ramp.